Communication device, information processing device, control method, and program

ABSTRACT

A communication device includes transmitting means for transmitting a signal in one or more frequency bands of a frequency channel including a plurality of frequency bands, identifying means for identifying occupancy of the plurality of frequency bands, and control means for controlling transmission power for transmitting the signal from the transmitting means, on the basis of an identification result obtained by the identifying means.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/JP2017/006132, filed Feb. 20, 2017, which claims the benefit ofJapanese Patent Application No. 2016-056018, filed Mar. 18, 2016, bothof which are hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a device that controls transmissionpower.

BACKGROUND ART

Communication devices that perform wireless communication conforming tothe IEEE 802.11 series are being widely used. Communication devicesconforming to the IEEE 802.11 series adopt an access scheme calledCSMA/CA (Carrier Sense Multiple Access with Collision Avoidance).CSMA/CA specifies that before transmission of signals, carrier sensingbe performed for measuring a radio field intensity for a frequencychannel on which the signals will be transmitted. In carrier sensing,the radio field intensity for a width of 20 MHz, which is one frequencychannel specified in IEEE 802.11, is measured.

As a result of carrier sensing, if the measured radio field intensitydoes not exceed a predetermined threshold, signals are transmitted; ifthe measured radio field intensity is greater than or equal to thepredetermined threshold, signals are not transmitted.

In IEEE, IEEE 802.11ax is under examination as a successor to IEEE802.11ac (PTL 1). In IEEE 802.11ax, it is being examined that onefrequency channel is further divided into a plurality of frequency bandsand the plurality of frequency bands are utilized by different devicesto perform communication simultaneously.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laid-Open No. 2015-165676

However, in a case where one frequency channel is further divided into aplurality of frequency bands and the plurality of frequency bands areutilized by different devices to perform communication simultaneously,it is conceivable that only some of the frequency bands are used forcommunication.

For example, in some cases, it is conceivable that a system that dividesone frequency channel into four frequency bands for utilization includesonly two devices that transmit data signals at a certain timing. In suchcases, only two of the four frequency bands may possibly be used.

In such cases, if the transmission power per unit frequency(transmission power density) of the respective devices is the same asthe transmission power density with which signals are transmitted usingall of the frequency bands of one frequency channel, the transmissionpower for the entire frequency channel is reduced to about half.

Thus, when another communication device performs carrier sensing inCSMA/CA, due to the low transmission power for the entire frequencychannel, the other communication device may fail to measure a radiofield intensity exceeding a predetermined threshold and may transmit asignal.

If another communication device transmits a signal, radio waveinterference occurs and an error is generated. In view of the issuedescribed above, it is an object to enable, when a signal is to betransmitted in one or more frequency bands of a frequency channelincluding a plurality of frequency bands, transmission of the signalwith transmission power suitable for the entire frequency channelcondition.

SUMMARY OF INVENTION

A communication device of the present invention includes transmittingmeans for transmitting a signal in one or more frequency bands of afrequency channel including a plurality of frequency bands, identifyingmeans for identifying occupancy of the plurality of frequency bands, andcontrol means for controlling transmission power for transmitting thesignal from the transmitting means, on the basis of an identificationresult obtained by the identifying means.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a network configuration diagram.

FIG. 2 is a hardware configuration diagram of a communication device.

FIG. 3 is a diagram illustrating a relationship between frequencies andRUs.

FIG. 4 is a diagram illustrating a relationship between frequencies andRUs.

FIG. 5 is a flowchart implemented by the communication device.

FIG. 6 is a flowchart implemented by the communication device.

FIG. 7 is a flowchart implemented by a base station.

DESCRIPTION OF EMBODIMENTS First Embodiment

FIG. 1 illustrates a communication system in this embodiment. A basestation 110 is an access point conforming to the IEEE 802.11 series andforms a wireless network 100. In this embodiment, the base station 110will be described as forming the wireless network 100 conforming to IEEE802.11ax and performing wireless communication conforming to IEEE802.11ax. Here, IEEE is an abbreviation of the Institute of Electricaland Electronics Engineers, Inc.

A communication device 101 is a subsidiary station that takes part inthe wireless network 100 formed by the base station 110. Thecommunication device 101 performs wireless communication conforming toIEEE 802.11ax with the base station 110 over the wireless network 100. Aplurality of communication devices 102 also take part in the wirelessnetwork 100 as subsidiary stations and perform wireless communicationconforming to IEEE 802.11ax with the base station 110.

A communication device 103 is a legacy terminal that does not supportIEEE 802.11ax, and performs wireless communication conforming to atleast any one of IEEE 802.11a, b, g, n, and ac.

The communication device 103, which is a legacy terminal, performscommunication in accordance with the DSSS scheme or the OFDM scheme,whereas the communication devices 101 and 102 and the base station 110perform communication in accordance with the OFDMA scheme. Thus, if thecommunication device 103 receives signals from the communication devices101 and 102 and the base station 110, the communication device 103 isunable to recognize the signals as data signals. DSSS is an abbreviationof Direct Sequence Spread Spectrum. OFDM is an abbreviation ofOrthogonal Frequency Division Multiplexing. OFDMA is an abbreviation ofOrthogonal Frequency-Division Multiple Access.

Thus, the communication device 103, which is a legacy terminal, uses anaccess scheme called CSMA/CA (Carrier Sense Multiple Access withCollision Avoidance) to prevent interference.

Specifically, before transmitting a signal, the communication device 103performs carrier sensing for measuring a radio field intensity of afrequency channel on which the signal will be transmitted. In carriersensing, the radio field intensity for a width of 20 MHz, which is onefrequency channel specified in IEEE 802.11, is measured.

If the measured radio field intensity does not exceed a predeterminedthreshold, it is determined that no other communication device isperforming communication on the frequency channel, and the communicationdevice 103 transmits the signal. If the measured radio field intensityis greater than or equal to the predetermined threshold, on the otherhand, it is determined that any other communication device is performingcommunication on the frequency channel, and the communication device 103does not transmit the signal. Thus, the communication device 103 isprevented from interfering with other communication devices.

FIG. 2 illustrates a hardware configuration of the communication device101. The base station 110 and the other communication devices 102 areassumed to also have similar hardware configurations.

A storage unit 201 is constituted by a memory such as a ROM or a RAM andstores programs for performing various operations described below andvarious types of information such as communication parameters forwireless communication. The storage unit 201 may be implemented using astorage medium such as a flexible disk, a hard disk, an optical disk, amagneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a non-volatilememory card, or a DVD, other than a memory such as a ROM or a RAM. Thestorage unit 201 may include a plurality of memories and the like.

A control unit 202 is constituted by a processor such as a CPU or an MPUand executes a program stored in the storage unit 201 to control theentire communication device 101. The control unit 202 may control theentire communication device 101 by cooperation of a program and an OS(Operating System) stored in the storage unit 201. Alternatively, thecontrol unit 202 may include a plurality of processors such as amulti-core processor and may control the entire communication device 101by using the plurality of processors.

Further, the control unit 202 controls a function unit 203 to execute apredetermined process such as capturing an image, printing, orprojection. The function unit 203 is a hardware component for allowingthe communication device 101 to execute a predetermined process. Forexample, when the communication device 101 is a camera, the functionunit 203 is an image capturing unit and performs an image capturingprocess. For example, when the communication device 101 is a printer,the function unit 203 is a printing unit and performs a printingprocess. For example, when the communication device 101 is a projector,the function unit 203 is a projection unit and performs a projectionprocess. The data to be processed by the function unit 203 may be datastored in the storage unit 201 or data received from any othercommunication device via a communication unit 206 described below.

An input unit 204 accepts various operations from a user. An output unit205 provides various outputs to the user. The outputs provided by theoutput unit 205 include at least one of screen display, audio outputthrough speakers, vibration output, and so on. Both the input unit 204and the output unit 205 may be implemented as a single module, such as atouch panel.

The communication unit 206 controls wireless communication conforming tothe IEEE 802.11 series or controls TCP/IP communication or the like.Further, the communication unit 206 controls an antenna 207 to transmitand receive a wireless signal for wireless communication. Thecommunication device 101 communicates content such as image data,document data, or video data to other communication devices via thecommunication unit 206.

Next, a method for IEEE 802.11ax communication, which is currently underexamination, will be described with reference to FIG. 3. In IEEE802.11ax, in addition to an existing scheme for providing communicationusing an entire single frequency channel, the following communicationscheme is being examined. It is being examined that a width of 20 MHz,which has been previously used as one frequency channel, is divided intoa plurality of frequency bands and that the plurality of frequency bandsare simultaneously utilized by different communication devices forcommunication. Here, each of the plurality of frequency bands isreferred to as an RU (Resource Unit). In this embodiment, one frequencychannel 302 (with a width of 20 MHz) is divided into four RUs, and eachRU 303 will be described as having a width of 5 MHz.

To enable a plurality of communication devices to simultaneously utilizea plurality of RUs, an access point transmits a trigger frame (TF) 301.A trigger frame is transmission permission to be granted to one or morecommunication devices. The trigger frame includes information on acommunication device to which each RU is allocated. Specifically, thetrigger frame includes a list in which RUs and AIDs, each of which isidentification information of a communication device, are associatedwith each other. AID is an abbreviation of Association Identifier.

The communication device(s) granted transmission permission by a triggerframe transmits a data frame signal 304 in a designated RU when an SIFStime period has elapsed since the reception of the trigger frame. SIFSis an abbreviation of Short Inter Frame Space and is a minimum waitingtime for a signal to be transmitted. AIFS, DIFS, PIFS, EIFS, or the likemay be used instead of SIFS. AIFS is an abbreviation of ArbitrationInter Frame Space, and DIFS is an abbreviation of Distributed InterFrame Space. PIFS is an abbreviation of Point Inter Frame Space, andEIFS is an abbreviation of Extended Inter Frame Space. In IEEE 802.11ax,when transmitting data signals, a plurality of communication devicesperform communication in accordance with the OFDMA scheme to improvefrequency utilization efficiency.

Further, the transmission power per unit frequency width (transmissionpower density) of a signal to be transmitted from the communicationdevice(s) granted transmission permission is the same as thetransmission power density for communication using the entire singlefrequency channel. Thus, the transmission power for transmitting asignal using one RU is lower than the transmission power forcommunication using the entire single frequency channel. Accordingly,for example, even if four communication devices each transmit a signalby using an RU, the transmission power per frequency channel can beequivalent to the transmission power for communication using the entiresingle frequency channel. Thus, for example, an excessive interferencewith other networks or an excess of statutorily specified power, whichis caused by an excessive increase in transmission power per frequencychannel, is avoidable.

IEEE 802.11ax also enables concurrent use of a plurality of frequencychannels for communication. FIG. 4 illustrates the use of four frequencychannels for communication. In this case, 16 RUs can be used.

FIG. 5 illustrates a flowchart of a process flow implemented by thecontrol unit 202 reading and executing a program stored in the storageunit 201 when the communication device 101 transmits a data signal.

It should be noted that at least a portion of the flowchart illustratedin FIG. 5 may be implemented by hardware. In the implementation byhardware, for example, a predetermined compiler may be used toautomatically generate a dedicated circuit on an FPGA in accordance witha program for implementing each step. FPGA is an abbreviation of FieldProgrammable Gate Array. Alternatively, a Gate Array circuit may beformed in a way similar to that on the FPGA to achieve implementation ashardware. The implementation may be achieved by an ASIC (ApplicationSpecific Integrated Circuit).

First, the communication device 101 waits for a trigger frame from thebase station 110 (S501). Upon receipt of a trigger frame (Yes in S501),the communication device 101 transmits a data signal after the lapse ofan SIFS time period (S502). Here, the communication device 101 transmitsa data signal in an RU for the communication device 101, which isdesignated by the trigger frame.

Then, the communication device 101 checks, in parallel to thetransmission of the data signal, a radio field intensity for an entirefrequency channel that is being used by the communication device 101 totransmit the signal (S503). This check is performed by the communicationunit 206 of the communication device 101 performing reception at thesame time as transmission and checking a radio field intensity for anentire frequency channel that is being used by the communication device101 to transmit the signal.

When the communication unit 206 of the communication device 101separately includes a transmitter and a receiver, the transmitter maytransmit the data signal and the receiver may check a radio fieldintensity for an entire frequency channel that is being used by thecommunication device 101 to transmit the signal.

In the check of the radio field intensity described above, the radiofield intensity for the entire frequency channel may be checked only fordata signals that are being communicated via wireless communication withthe base station 110. This operation is achieved by determining a sum ofthe radio field intensities of data signals received in the respectiveRUs.

As a result of the check, if the radio field intensity for the entirefrequency channel is less than a predetermined threshold (No in S504),the communication device 101 transmits the data signal with increasedtransmission power (S505). Here, the communication device 101 transmitsthe data signal with the power increased by an amount by which the radiofield intensity for the entire frequency channel is short of thepredetermined threshold.

The predetermined threshold described above is the same as apredetermined threshold used by the communication device 103 duringcarrier sensing.

If the radio field intensity for the entire frequency channel is lessthan the predetermined threshold, it is determined that no othercommunication device is performing communication on the frequencychannel when the communication device 103 performs carrier sensing, andthe communication device 103 transmits a signal. If the communicationdevice 103 transmits a signal, the signal may interfere with the signalto be transmitted from the communication device 101, and an error can begenerated. Thus, the communication device 101 increases the transmissionpower of the signal to enhance the radio field intensity for the entirefrequency channel. Thus, it is more likely that carrier sensingperformed by the communication device 103 estimates that any othercommunication device is performing communication on the frequencychannel, which increases the probability that the communication device103 will not transmit a signal. As a result, the generation of an errordue to interference can be prevented.

The following two can be conceived as methods for allowing thecommunication device 101 to increase the transmission power. The firstmethod is to increase the transmission power density for transmission inthe RU for the communication device 101. The second method is totransmit a signal also in another RU in addition to the RU for thecommunication device 101. In this case, in the other RU, thecommunication device 101 may transmit the same data as that in the RUfor the communication device 101 or different data from the RU for thecommunication device 101 or may transmit dummy data.

The first method enhances the transmission power of the data signal andcan thus have an effect of further improving communication quality. Thesecond method can improve the transmission power even when, for example,an upper limit is defined on the transmission power density fortransmission in one RU due to hardware restrictions or statutoryrestrictions.

Which of these methods to use may be determined in advance or thesemethods may be switched between in accordance with the situation. Forexample, if the radio field intensity for the entire frequency channelis less than the predetermined threshold even when the transmissionpower density is enhanced within hardware restrictions or statutoryrestrictions, the second method may be performed or, otherwise, thefirst method may be performed. In addition, also when the second methodis performed, the transmission power density in the RU for thecommunication device 101 may be enhanced as appropriate.

On the other hand, if the radio field intensity for the entire frequencychannel is greater than or equal to the predetermined threshold (Yes inS504), the communication device 101 continues the transmission of thedata signal without increasing the transmission power (S506).

When the transmission of the data signal is completed, the communicationdevice 101 receives a confirmation response to the data signal, namely,Ack, from the base station (S507). The Ack is transmitted using theentire single frequency channel. The Ack also serves as a confirmationresponse to a data signal transmitted from another communication device102 via another RU in synchronization with the transmission of the datasignal from the communication device 101.

Then, the process illustrated in FIG. 5 ends. If data to be transmittedby the communication device 101 is generated or if there remains data tobe transmitted, the process returns to the first step in FIG. 5.

In S503, instead of the radio field intensity for the entire frequencychannel, the occupancy of each RU may be checked to determine the numberof RUs that are not being used for signal transmission. In this case, inS504, the communication device 101 determines whether the number of RUsthat are not being used for signal transmission is greater than or equalto a predetermined value. The predetermined value is assumed to be setsuch that the radio field intensity for the entire frequency channel isless than the predetermined threshold if the number of RUs that are notbeing used is greater than or equal to the predetermined value. Thus, ifthe number of RUs that are not being used is greater than or equal tothe predetermined value, the radio field intensity for the entirefrequency channel is greater than or equal to the predeterminedthreshold.

As a result of the determination in S504, if the number of RUs that arenot being used for signal transmission is greater than or equal to thepredetermined value, the process proceeds to S505; if the number of RUsthat are not being used for signal transmission is less than thepredetermined value, the process proceeds to S506. This can also achievesimilar advantages.

Further, in this case, in S505, the amount of increase in transmissionpower may be controlled in accordance with the number of RUs that arenot being used for signal transmission. For example, if it is determinedthat two RUs out of the four RUs are not being used, the transmissionpower is doubled; if it is determined that three RUs out of the four RUsare not being used, the transmission power is quadrupled. If it is notpossible to quadruple the transmission power due to the constraints ofthe hardware of the communication device 101 or due to statutoryconstraints, the maximum transmission power that satisfies theseconstraints may be used.

Thus, preventing other communication devices from transmitting signalsfurther in view of a balance to be achieved over the transmission powerfor communication using an entire single frequency channel can preventthe generation of an error due to interference with the othercommunication devices. That is, for example, an excessive interferencewith communication over other networks or an excess of statutorilyspecified power, which is caused by an excessive increase intransmission power for each frequency channel, is avoidable. Inaddition, interference with other communication devices is avoidable.

Instead of the number of RUs that are not being used for signaltransmission, the number of RUs that are being used for signaltransmission may be determined. Also in this case, a predetermined valueis determined appropriately, and if the number of RUs that are beingused for signal transmission is greater than or equal to thepredetermined value, the process proceeds to S506; if the number of RUsthat are being used for signal transmission is less than thepredetermined value, the process proceeds to S505. Thus, similaradvantages can be achieved.

Second Embodiment

In the first embodiment, the communication device 101 measures a radiofield intensity and the availability of the RUs in parallel to thetransmission of a data signal. In a second embodiment, the communicationdevice 101 checks the availability of the RUs on the basis ofinformation included in a trigger frame.

Also in the second embodiment, the system configuration and the hardwareconfiguration of each device are similar to those in the firstembodiment and will not be described herein.

FIG. 6 illustrates a flowchart of a process flow implemented by thecontrol unit 202 reading and executing a program stored in the storageunit 201 when the communication device 101 transmits a data signal.

First, the communication device 101 waits for a trigger frame from thebase station 110 (S601). Upon receipt of a trigger frame (Yes in S601),the communication device 101 analyzes the trigger frame and determinesthe number of RUs to be used to transmit a data signal (S602). Asdescribed in the first embodiment, the trigger frame includes a list inwhich AIDs, each of which is identification information of acommunication device that is granted transmission permission, and RUsare associated with each other. Thus, the communication device 101 candetermine the number of RUs to be used to transmit a data signal on thebasis of the trigger frame.

If the number of RUs that are being used for signal transmission isgreater than or equal to the predetermined value (Yes in S603), thecommunication device 101 transmits a data signal with transmission powersimilar to that in S502 in FIG. 5 (S604). On the other hand, if thenumber of RUs that are being used for signal transmission is less thanthe predetermined value (No in S603), the communication device 101transmits a data signal with transmission power higher than thetransmission power in S604 (S605).

For example, the predetermined value is 3. In this case, if it isdetermined that, of four RUs, three RUs are being used and one RU is notbeing used, the data signal is transmitted with the same transmissionpower density as that during communication using an entire singlefrequency channel. Thus, the transmission power of the communicationdevice 101 is reduced to approximately a quarter of that duringcommunication using the entire single frequency channel.

When it is determined that, of the four RUs, two RUs are being used andtwo RUs are not being used, the transmission power density is doubled.Thus, in this case, the transmission power of the communication device101 is twice the transmission power in S502.

When it is determined that, of the four RUs, one RU is being used andthree RUs are not being used, the transmission power density isquadrupled. Thus, in this case, the transmission power of thecommunication device 101 is four times the transmission power in S502.If it is not possible to quadruple the transmission power due tohardware constraints of the communication device 101 or due to statutoryconstraints, the maximum transmission power that satisfies theseconstraints may be used.

When the transmission of the data signal is completed, the communicationdevice 101 receives a confirmation response to the data signal, namely,Ack, from the base station (S606). Then, the process illustrated in FIG.6 ends. If data to be transmitted by the communication device 101 isgenerated or if there remains data to be transmitted, the processreturns to the first step in FIG. 6.

In the way described above, the communication device 101 controlstransmission power on the basis of information included in a triggerframe, and the generation of an error due to interference can beprevented.

In some cases, it is conceivable that communication devices utilize RUsin an autonomous and distributed way and that the base station 110 doesnot specify the devices that utilize the RUs. In such cases, the basestation 110 assigns a value (for example, 0) of the AID in a triggerframe, indicating that a device that utilizes an RU is not specified.The base station 110 may not specify a device for any of the RUs or maynot specify a device for some of the RUs.

If devices that utilize at least some of the RUs are not specified, thecommunication device 101 is unable to determine whether signals will betransmitted in the RUs to be utilized by the unspecified devices on thebasis of the trigger frame. Thus, processes may be switched between suchthat the process illustrated in the first embodiment is performed in thecase described above or, otherwise, the process illustrated in thesecond embodiment is performed.

If information on the AID included in the trigger frame is notsuccessfully acquired, the process illustrated in the first embodimentmay be performed or, otherwise, the process illustrated in the secondembodiment may be performed or the process may proceed to the switchingprocess described above. Cases where information on the AID included inthe trigger frame is not successfully acquired include a case where thetrigger frame does not include information on the AID, and a case wherea communication error has caused the failure to obtain information onthe AID included in the trigger frame.

Thus, if it is possible to check the availability of the RUs on thebasis of information included in the trigger frame, power control can beperformed on the basis of the information in the trigger frame; if it isnot possible to check the availability of the RUs, power control can beperformed on the basis of the measurement results of the radio fieldintensity or the availability of the RUs. Accordingly, a power controlprocess suitable for a trigger frame can be performed.

Third Embodiment

In the first and second embodiments, the communication device 101 checksthe radio field intensity or the availability of the RUs. In a thirdembodiment, the base station 110 determines the transmission power ofeach communication device on the basis of the availability of the RUs.

Also in the third embodiment, the system configuration and the hardwareconfiguration of each device are similar to those in the firstembodiment and will not be described herein.

FIG. 7 illustrates a flowchart of a process flow implemented by thecontrol unit 202 of the base station 110 reading and executing a programstored in the storage unit 201 of the base station 110 when the basestation 110 transmits a trigger frame.

Before the process illustrated in FIG. 7, the base station 110 receivesfrom the communication devices 101 and 102 a transmission request for adata signal. Then, the base station 110 determines, based on thereceived transmission request, communication devices that performcommunication at the same timing and allocates an RU to each of thecommunication devices (S701). The base station 110 may determinecommunication devices that perform communication at the same timing onthe basis of, in addition to the transmission request, the positions ofthe communication devices 101 and 102 or the radio wave environment.

Then, the base station 110 determines the transmission power of eachcommunication device on the basis of the number of RUs used by thecommunication devices that perform communication at the same timing(S702). For example, when, of four RUs, two RUs are used and two RUs arenot used, the base station 110 determines transmission power such thatthe transmission power density of each communication device becomesdouble. When, of the four RUs, one RU is used and three RUs are notused, the base station 110 quadruples the transmission power density ofeach communication device. Thus, in this case, the transmission power isfour times the transmission power in S502. If it is not possible toquadruple the transmission power due to hardware constraints of thecommunication device 101 or due to statutory constraints, the maximumtransmission power that satisfies these constraints may be used.

In the example described above, the respective transmission powers ofthe communication devices are the same, which is not intended to belimiting. The transmission power may differ from one communicationdevice to another. In this case, the base station 110 determines thetransmission power of each communication device such that a radio fieldintensity exceeding a predetermined threshold that is used by thecommunication device 103 during carrier sensing can be achieved for theentire frequency channel.

For example, the base station 110 obtains information on the hardware ofeach communication and determines the transmission power of eachcommunication device on the basis of the obtained information.Consideration is given to a case where, for example, two RUs out of fourRUs are utilized and transmission permission is granted to a device forwhich the transmission power density can be quadrupled and a device forwhich the transmission power density is not increasable. In this case,the base station 110 determines that the transmission power ismultiplied by three for the device for which the transmission powerdensity can be quadrupled, and determines that the transmission powerdensity is multiplied by one for the device for which the transmissionpower density is not increasable. Thus, a radio field intensityexceeding a predetermined threshold that is used by the communicationdevice 103 during carrier sensing can be achieved for the entirefrequency channel while the hardware constraints of each device aresatisfied.

Further, for example, the base station 110 may determine eachtransmission power on the basis of the reception quality of a signalfrom each communication device. Specifically, the base station 110determines that the transmission power is increased for a device withlow reception quality, compared with a device with high receptionquality. Also in this case, the base station 110 determines thetransmission power of each communication device such that a radio fieldintensity exceeding a predetermined threshold that is used by thecommunication device 103 during carrier sensing can be achieved for theentire frequency channel. As the reception quality, the signal intensitymay be used or a result of channel estimation between the base station110 and communication devices (for example, a value determined by thecalculation of an eigenvalue of a channel matrix). Thus, thetransmission power of a device with low reception quality is increasedto enhance reception quality, and a radio field intensity exceeding apredetermined threshold that is used by the communication device 103during carrier sensing can be achieved for the entire frequency channel.

Further, for example, the base station 110 may randomly determine thetransmission power of each communication device while achieving, for theentire frequency channel, a radio field intensity exceeding apredetermined threshold that is used by the communication device 103during carrier sensing. Thus, power consumption required for eachcommunication device to transmit data can be made approximately uniform,on average, over a long period of time.

Then, the base station 110 transmits a trigger frame including thetransmission power of each communication device determined in S702(S703). Note that a device for which the transmission power isdetermined in S702 not to be increased may not be given an instructionregarding transmission power. Additionally, the base station 110 maynotify each communication device of the transmission power of eachcommunication device, which is determined in S702, as a separate signalfrom the trigger frame.

Upon receipt of the trigger frame, each communication device transmits adata signal on the basis of the transmission power specified in thetrigger frame.

This can prevent the generation of an error due to interference, furtherin view of a balance to be achieved over the transmission power forcommunication using an entire single frequency channel, withoutrequiring each communication device to determine the transmission power.

Also in the embodiment described above, the following two can beconceived as methods for allowing a communication device to increase thetransmission power. The first method is to increase the transmissionpower density for transmission in the RU for the communication device.The second method is to transmit a signal also in another RU in additionto the RU for the communication device. In this case, the base station110 designates which communication device uses an RU and which RU is tobe used. For example, a device that is requested by each device totransmit a large amount of data is determined to be a device thattransmits a signal also in another RU, and this device is instructed toalso use the other RU. Then, the device transmits data by using the twoRUs. This can enhance the transmission power for the entire frequencychannel and can enhance data transmission efficiency.

Which of the methods to use as a method for allowing a communicationdevice to increase the transmission power may be determined in advance,or the methods may be switched between in accordance with the situation.For example, if the radio field intensity for the entire frequencychannel is less than the predetermined threshold even when thetransmission power density is enhanced within hardware restrictions orstatutory restrictions, the second method may be performed or,otherwise, the first method may be performed.

In the embodiment described above, furthermore, the transmission powerof each communication device is determined on the basis of theavailability of the RUs. However, this is not intended to be limiting.Any other information processing device different from the base stationmay determine communication devices that perform communication at thesame timing by the base station 110, on the basis of a transmissionrequest from each communication device, allocate an RU to each of thecommunication devices, and further determine the transmission power. Inthis case, the content of the determination is transmitted to thecommunication devices via the base station 110. This can also achievesimilar advantages.

The present invention can also be implemented using a process forproviding a program that implements one or more functions in theembodiments described above to a system or device via a network or astorage medium and for reading and executing the program by one or moreprocessors in a computer of the system or device. The present inventioncan also be implemented by a circuit (for example, an ASIC) thatimplements one or more functions.

The present invention is not limited to the embodiments described aboveand can be variously changed and modified without departing from thespirit and scope of the present invention. Thus, the following claimsare appended to make the scope of the present invention public.

According to the present invention, when a signal is to be transmittedin one or more frequency bands of a frequency channel including aplurality of frequency bands, the signal can be transmitted withtransmission power suitable for the entire frequency channel condition.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1-20. (canceled)
 21. A communication device comprising: one or moreprocessors; and one or more memories including instructions that, whenexecuted by the processor(s), cause the communication device to: receivea trigger frame including information on a plurality of resource unitsfrom a base station; and transmit a data signal to the base station in aresource unit designated for the communication device by the triggerframe with transmission power determined based on signal quality betweenthe communication device and the base station, wherein the communicationdevice transmits the data signal with first transmission power when thesignal quality is a first quality, and transmits the data signal withsecond transmission power higher than the first transmission power whenthe signal quality is a second quality lower than the first quality. 22.The communication device according to claim 21, wherein the triggerframe includes information for allowing the communication device totransmit the data signal with the transmission power.
 23. Thecommunication device according to claim 21, wherein the trigger frameincludes information in which a resource unit used by the communicationdevice to transmit the data signal and an Association Identifier of thecommunication device are associated with each other.
 24. Thecommunication device according to claim 21, wherein the communicationdevice transmits the data signal when an SIFS (Short Inter Frame Space)time period elapses after the trigger frame is received.
 25. Thecommunication device according to claim 21, wherein the trigger frame isa signal conforming to an IEEE 802.11 series.
 26. A method ofcontrolling a communication device, the method comprising: receiving atrigger frame including information on a plurality of resource unitsfrom a base station; determining a signal quality between thecommunication device and the base station; transmitting, based on adetermined signal quality being a first signal quality, a data signalwith a first transmission power to the base station in a resource unitdesignated for the communication device by the trigger frame; andtransmitting, based on a determined signal quality being a second signalquality lower than the first signal quality, a data signal with a withsecond transmission power higher than the first transmission power tothe base station in a resource unit designated for the communicationdevice by the trigger frame.
 27. A non-transitory computer readablestorage medium storing instructions that, when executed by one or moreprocessors, causes a communication device to execute a control method,the control method comprising: receiving a trigger frame includinginformation on a plurality of resource units from a base station;determining a signal quality between the communication device and thebase station; transmitting, based on a determined signal quality being afirst signal quality, a data signal with a first transmission power tothe base station in a resource unit designated for the communicationdevice by the trigger frame; and transmitting, based on a determinedsignal quality being a second signal quality lower than the first signalquality, a data signal with a with second transmission power higher thanthe first transmission power to the base station in a resource unitdesignated for the communication device by the trigger frame.